Department of Medicine , University of Texas Health Science Center at San Antonio .
Mol Cell Biochem 140 : 31-6 ( 1994)
Abstract
We have investigated the effect of phorbol 12-myristate 13-acetate ( PMA ) on platelet-derived growth factor ( PDGF ) B-chain gene transcription as well as on mRNA stability in cultured human mesangial cells .
Addition of actinomycin to cells stimulated with PMA decreases steady state levels of PDGF-B chain mRNA analysed by solution hybridization assay .
PDGF-B chain gene transcription was also assayed directly by measuring elongation of transcripts in isolated nuclei followed by hybridization of labeled RNA transcripts to a cDNA encoding for PDGF-B chain .
Our data show that PMA induces PDGF-B chain gene transcription by approximately 2-fold .
alpha-Amanitin , an RNA polymerase II inhibitor , blocked transcription by more than 70% .
In addition , we determined the effect of PMA on the halflife of PDGF-B chain mRNA directly by pulse chase method .
In human mesangial cells , the PDGF-B chain mRNA exhibited halflife of approximately 105 min.
In the presence of PMA , the halflife of PDGF-B chain mRNA was reduced to approximately min.
These studies indicate that regulation of PDGF-B chain gene by PMA in human mesangial cells involves a coordinate effort at the level of transcription and mRNA stability .